Because of integration, mobile devices, including mobile phones and other mobile terminal devices such as PDA's (personal digital assistants) and pocket computers, are getting smarter, smaller and offer more and more different functions. This leads to the requirement of more extended and versatile input devices such as keyboards. At the same time, however, the size of the mobile terminal devices has to remain the same or even get smaller. The need for relatively large keyboards for small mobile terminal devices is growing all the time when mobile terminal devices decrease in size. Existing solutions encompass foldable mobile terminal devices, or if more applications are needed, solutions such as the Nokia Communicator.
The problems with current NOKIA® Communicators (9000,9110,9210, . . . ) is that the clamshell concept begins to reach its limits and does not allow extended options. The biggest problem may be the total thickness of the device. Especially with two displays (and double sided printed wire board) more size is needed and the product is more expensive. Although practical, its big size does not agree to everyone's taste. Mechanism for two displays and a keyboard and a keypad, however does not make it very easy to decrease the size of the phone.
Prior attempts of foldable mobile terminal devices are described e.g. in the patent documents WO9819434, and WO0153919. From WO9819434 there is known a mobile electronic device (MED) comprising: a keyboard with an operative surface, a cover having at least one transparent area, and a display element having a display surface. The mobile phone described therein has a keyboard, located on a foldable cover with a transparent area, and is operable in the open and in the closed position. The display element incorporated in the body of the device is visible through a transparent area of the cover in the closed position, but it is just another example of the traditional clamshell construction that has been used for years. The device described in WO9819434 further has the drawback that the device can not be used on a desk in laptop fashion, because the display is incorporated in the body of the device so the device would tilt when opened and placed on a table.
In WO0153919 a convertible modular PDA is described. It has three parts but these parts are attached with hinges to the central part and by switching their positions, different modes are available. The device in this document needs at least two displays to provide the desired functionality.